This game is nearly perfect. The control is fantastic, the camera rarely gets in your way, the game never made me want to quit, the music is a joy to listen to, and Mario's new moves are very welcome edition.
The story is pretty simple, Mario is on his way to the star festival, but Bowser kidnaps the princess (big surprise) and as Mario you have to save her, but you come across the Lumas who live on a space ship that orbits the Earth and power their ship with the power of a bunch of Grand Stars that also helps the Lumas live. Bowser takes all of the Grand Stars to beat Mario once and for all. Mario then gets all of the Grand Stars back to save the Lumas, beat Bowser, and save Peach. It's your basic Mario story and nobody plays Mario games for their story anyway, so lets talk about the gameplay.
Mario can still jump on enemies, do the ground pound, and still has a life bar. Mario's new moves include the spin attack, the star bits, the bee mushroom which allows Mario to fly for a short time and stick to honeycombs, the boo mushroom which allows Mario to become a Boo, allowing them to go through fences and read Booish, and the spring mushroom which lets Mario jump higher, the health mushroom which increases Mario's life bar from 3 to 6, and of course the star. The spin attack makes dealing with enemies a lot easier, the star bits are a good way to deal with enemies and collecting 50 gets you an extra life, and just jumping is still easy an effective way to kill enemies.
The only complaint I have with this game is that I wish it had a better multiplayer option, but there are too many good things to make a big impact on the game. It definitely deserves my recommendation for any wii owner and anyone who wants to try out a 3D Mario game, start with this one. It is one of my favorite games of all time.